Overview of Serum Uric Acid Treatment Targets in Gout: Why Less Than 6 mg/dL?

Exercise and hyperuricemia: an opinion article

Hyperuricaemia (HUA) is an abnormally high concentration of serum urate caused by either an excess of uric acid production or decreased excretion capacity in the body. Serum urate concentration forms sodium salts that deposit in the soft tissues of the joints, ultimately leading to gout. Additionally, HUA is strongly associated with several acute and chronic illnesses. In various clinical guidelines and practices, xanthine oxidase inhibitors, such as allopurinol and febuxostat, are commonly used as the initial medication for treating HUA. However, extended usage of urate-lowering drugs may have risks, including cardiovascular thrombotic events and hepatic impairment. Implementing a scientifically informed fitness diet in conjunction with appropriate exercise may decrease HUA. Unfortunately, there is currently a shortfall in exercise intervention trials for individuals suffering from HUA. Most of the previous evidence suggesting that exercise improves serum urate levels comes from intervention trials in other populations, and serum urate is only one of the outcomes observed. This opinion article analyses the causes of HUA, offers dietary and exercise guidance with the aim of furnishing a point of reference for individuals with HUA or fitness enthusiasts.

Patient factors and health outcomes associated with illness perceptions in people with gout

OBJECTIVE

Illness perceptions are views and beliefs formed in response to a health threat, and they may influence self-management behaviours and chronic disease outcomes. Despite effective medication, sub-optimal outcomes in gout are common. This study aimed to quantitatively investigate illness perceptions in gout to examine how illness perceptions relate to health outcomes.

METHODS

Data were obtained from a randomized controlled trial in which people with gout (n = 493) completed surveys measuring illness perceptions [Brief Illness Perception Questionnaire (B-IPQ)], gout flares, medication adherence, health-related quality of life, health-care utilization, and productivity, alongside serum urate blood tests at baseline, and at 6- and 12-month follow-ups. Multivariable linear regression identified patient factors independently associated with each B-IPQ item score. Logistic and linear regression, adjusted for age and sex, determined whether baseline B-IPQ items could predict current and future health outcomes.

RESULTS

Younger individuals and those with severe gout were more likely to experience pessimistic illness perceptions at baseline. Optimistic illness perceptions were associated with lower odds of having had at least one flare in the preceding 6 months. Every 1-point increase in B-IPQ treatment control, indicating an increasingly optimistic view that gout is treatable, decreased the odds of a recent flare prior to baseline by 33% [odds ratio (OR): 0.67; 95% CI: 0.53, 0.85; P < 0.001] and prior to the 12-month follow-up by 15% (OR: 0.85; 95% CI: 0.76,0.96; P = 0.01). Pessimistic illness perceptions also predicted poorer medication adherence, health-related quality of life, and productivity, but not serum urate levels.

CONCLUSION

Modifying pessimistic illness perceptions, including, but not limited to, patient education, may promote prudent self-management behaviours and better outcomes in gout.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry; https://www.anzctr.org.au/, ACTRN12616000455460.

The COMPARE head-to-head, randomized controlled trial of SEL-212 (pegadricase plus rapamycin-containing nanoparticle, ImmTOR™) versus pegloticase for refractory gout

OBJECTIVES

Serum urate (SU) lowering with PEGylated uricases in gout can reduce flares and tophi. However, treatment-emergent anti-drug antibodies adversely affect safety and efficacy and the currently approved PEGylated uricase pegloticase requires twice-monthly infusions. Investigational SEL-212 therapy aims to promote uricase-specific tolerance via monthly sequential infusions of a proprietary rapamycin-containing nanoparticle (ImmTOR) and pegadricase.

METHODS

COMPARE was a randomized, phase 2, open-label trial of SEL-212 vs pegloticase in adults with refractory gout. SEL-212 [ImmTOR (0.15 mg/kg) and pegadricase (0.2 mg/kg)] was infused monthly or pegloticase (8 mg) twice monthly for 6 months. The primary endpoint was the proportion of participants with SU <6 mg/dl for ≥80% of the time during 3 and 6 months. Secondary outcomes were mean SU, gout flares, number of tender and/or swollen joints and safety.

RESULTS

During months 3 and 6 combined, numerically more participants achieved and maintained a SU <6 mg/dl for ≥80% of the time with SEL-212 vs pegloticase (53.0% vs 46.0%, P = 0.181). The percentage reductions in SU levels were statistically greater during months 3 and 6 with SEL-212 vs pegloticase (-73.79% and -47.96%, P = 0.0161). Reductions in gout flare incidence and number of tender and/or swollen joints were comparable between treatments. There were numerical differences between the most common treatment-related adverse events of interest with SEL-212 and pegloticase: gout flares (60.2% vs 50.6%), infections (25.3% vs 18.4%) and infusion-related reactions (15.7% vs 11.5%), respectively. Stomatitis (and related terms) was experienced by eight participants (9.6%) with SEL-212 and none with pegloticase. Stomatitis, a known event for rapamycin, was associated with ImmTOR only.

CONCLUSIONS

SEL-212 efficacy and tolerability were comparable to pegloticase in refractory gout. This was associated with a substantial reduction in treatment burden with SEL-212 due to decreased infusion frequency vs pegloticase.

CLINICAL TRIAL REGISTRATION

NCT03905512.

Mechanisms and rationale for uricase use in patients with gout

Xanthine oxidase inhibitors such as allopurinol and febuxostat have been the mainstay urate-lowering therapy (ULT) for treating hyperuricaemia in patients with gout. However, not all patients receiving oral ULT achieve the target serum urate level, in part because some patients cannot tolerate, or have actual or misconceived contraindications to, their use, mainly due to comorbidities. ULT dosage is also limited by formularies and clinical inertia. This failure to sufficiently lower serum urate levels can lead to difficult-to-treat or uncontrolled gout, usually due to poorly managed and/or under-treated gout. In species other than humans, uricase (urate oxidase) converts urate to allantoin, which is more soluble in urine than uric acid. Exogenic uricases are an exciting therapeutic option for patients with gout. They can be viewed as enzyme replacement therapy. Uricases are being used to treat uncontrolled gout, and can achieve rapid reduction of hyperuricaemia, dramatic resolution of tophi, decreased chronic joint pain and improved quality of life. Availability, cost and uricase immunogenicity have limited their use. Uricases could become a leading choice in severe and difficult-to-treat gout as induction and/or debulking therapy (that is, for lowering of the urate pool) to be followed by chronic oral ULT. This Review summarizes the evidence regarding available uricases and those in the pipeline, their debulking effect and their outcomes related to gout and beyond.

The Stiff Joint: Comparative Evaluation of Monotherapy and Combination Therapy With Urate Lowering Agents in Managing Acute Gout

Gout, an extremely painful form of arthritis, is triggered by the innate immune system's response to the accumulation of monosodium urate crystals in specific joints and surrounding tissues. This condition is characterized by recurring episodes of excruciating arthritis flares, interspersed with periods of disease quiescence. Over time, gout can result in disability, tophi formation, and severe pain. The treatment of gout is centered around two main objectives: alleviating inflammation and pain during acute gout attacks and long-term management to reduce serum urate levels and mitigate the risk of future attacks. Addressing inflammation and pain during acute attacks is often complicated by various factors, including underlying health conditions commonly associated with gout, such as hypertension, chronic kidney disease, cardiovascular disease, and diabetes mellitus. Moreover, gout patients are frequently older and have multiple coexisting health issues, necessitating complex medication regimens. Given the rising prevalence of gout and its associated comorbidities, there's a growing demand for improved treatment options. While existing treatments effectively manage gout in some patients, a significant portion, particularly those with comorbidities, face contraindications to these treatments and require alternative approaches. Innovative medications are required to enhance gout treatment, especially for individuals with concurrent health conditions. These considerations underscore the importance of reviewing both monotherapy and combination therapy approaches for acute gout treatment.

Identification of Xanthine Oxidase Inhibitors from Celery Seeds Using Affinity Ultrafiltration-Liquid Chromatography-Mass Spectrometry

Celery seeds have been used as an effective dietary supplement to manage hyperuricemia and diminish gout recurrence. Xanthine oxidase (XOD), the critical enzyme responsible for uric acid production, represents the most promising target for anti-hyperuricemia in clinical practice. In this study, we aimed to establish a method based on affinity ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) to directly and rapidly identify the bioactive compounds contributing to the XOD-inhibitory effects of celery seed crude extracts. Chemical profiling of celery seed extracts was performed using UPLC-TOF/MS. The structure was elucidated by matching the multistage fragment ion data to the database and publications of high-resolution natural product mass spectrometry. Thirty-two compounds, including fourteen flavonoids and six phenylpeptides, were identified from celery seed extracts. UF-LC-MS showed that luteolin-7-O-apinosyl glucoside, luteolin-7-O-glucoside, luteolin-7-O-malonyl apinoside, luteolin-7-O-6'-malonyl glucoside, luteolin, apigenin, and chrysoeriol were potential binding compounds of XOD. A further enzyme activity assay demonstrated that celery seed extract (IC50 = 1.98 mg/mL), luteolin-7-O-apinosyl glucoside (IC50 = 3140.51 μmol/L), luteolin-7-O-glucoside (IC50 = 975.83 μmol/L), luteolin-7-O-6'-malonyl glucoside (IC50 = 2018.37 μmol/L), luteolin (IC50 = 69.23 μmol/L), apigenin (IC50 = 92.56 μmol/L), and chrysoeriol (IC50 = 40.52 μmol/L) could dose-dependently inhibit XOD activities. This study highlighted UF-LC-MS as a useful platform for screening novel XOD inhibitors and revealed the chemical basis of celery seed as an anti-gout dietary supplement.

Sodium-Glucose Cotransporter 2 Inhibitors to Decrease the Uric Acid Concentration-A Novel Mechanism of Action

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) are glucose-lowering agents whose positive impact on cardiovascular risk has been described extensively. Not only do they influence lipid profile, blood pressure, atherosclerosis risk, hemoglobin level, and insulin resistance, but they also reduce cardiovascular events, all-cause mortality, and hospitalization rates. Some of these effects may be due to their impact on serum uric acid (SUA) concentration. Findings from nine meta-analyses showed that, indeed, SGLT2is significantly reduce SUA. The data on the drug- and dose-dependency of this effect were inconclusive. Several factors alternating the beneficial effects of SGLT2is on SUA, such as glycated hemoglobin concentration (HbA1c), presence of diabetes, and baseline SUA level, were described. Even though there is a consensus that the lowering of SUA by SGLT2is might be due to the increased urinary excretion rate of uric acid (UEUA) rather than its altered metabolism, the exact mechanism remains unknown. The influence of SGLT2is on SUA may not only be used in gout treatment but may also be of huge importance in explaining the observed pleiotropic effects of SGLT2is.

Wearable biosensors for human fatigue diagnosis: A review

Fatigue causes deleterious effects to physical and mental health of human being and may cause loss of lives. Therefore, the adverse effects of fatigue on individuals and the society are massive. With the ever-increasing frequency of overtraining among modern military and sports personnel, timely, portable and accurate fatigue diagnosis is essential to avoid fatigue-induced accidents. However, traditional detection methods require complex sample preparation and blood sampling processes, which cannot meet the timeliness and portability of fatigue diagnosis. With the development of flexible materials and biosensing technology, wearable biosensors have attracted increased attention to the researchers. Wearable biosensors collect biomarkers from noninvasive biofluids, such as sweat, saliva, and tears, followed by biosensing with the help of biosensing modules continuously and quantitatively. The detection signal can then be transmitted through wireless communication modules that constitute a method for real-time understanding of abnormality. Recent developments of wearable biosensors are focused on miniaturized wearable electrochemistry and optical biosensors for metabolites detection, of which, few have exhibited satisfactory results in medical diagnosis. However, detection performance limits the wide-range applicability of wearable fatigue diagnosis. In this article, the application of wearable biosensors in fatigue diagnosis has been discussed. In fact, exploration of the composition of different biofluids and their potential toward fatigue diagnosis have been discussed here for the very first time. Moreover, discussions regarding the current bottlenecks in wearable fatigue biosensors and the latest advancements in biochemical reaction and data communication modules have been incorporated herein. Finally, the main challenges and opportunities were discussed for wearable fatigue diagnosis in the future.

A Retrospective Study of the Perioperative Period Management of Joint Arthroplasty in Patients with Chronic Kidney Disease

OBJECTIVE

With the rising prevalence of chronic kidney disease (CKD) and the increasing demand for joint arthroplasty, the management of CKD patients in the perioperative period of joint arthroplasty has become an issue worthy of attention for orthopedic surgeons. This study aimed to explore comprehensive perioperative period management strategies for CKD patients.

METHODS

From March 2017 to August 2022, 62 patients who underwent joint arthroplasty in our hospital were included in a retrospective study, including 31 CKD patients (mean age 69.8 ± 13.4 years old) and 31 non-CKD patients (mean age 69.4 ± 14.2 years old). The outcome indicators were analyzed, including serum urea, serum creatinine, blood uric acid, hematocrit, and hemoglobin.

RESULTS

All patients included in the retrospective study had an average preoperative preparation time of 4.3 ± 2.6 days and an average hospitalization time of 11.0 ± 7.3 days. There were no significant differences in the changes in the serum urea values between the preoperative and postoperative measurements in the CKD patients or in the serum creatinine values and blood uric acid values (P > 0.05). The hemoglobin value in postoperative measurements was lower than in preoperative measurements in the CKD patients (P < 0.05). The hematocrit value in postoperative measurements was lower than in preoperative measurements in the CKD patients (P < 0.001).

CONCLUSION

Patients with CKD have distinct characteristics compared to non-CKD patients, and they generally have a higher risk for postoperative complications and adverse events. Recognition of risk factors, suitable timing of surgery, the undertaking of protective strategies, and proper management of complications are vital for managing CKD patients in the perioperative period of joint arthroplasty.

Identification of a plausible serum uric acid cut-off value as prognostic marker of stroke: the Uric Acid Right for Heart Health (URRAH) study

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting combined (fatal and non-fatal) cerebrovascular (CBV) events in the whole database. The URic acid Right for heArt Health study is a nationwide, multicenter, observational cohort study involving data on subjects aged 18-95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 120.7 ± 61.8 months. A total of 14,588 subjects were included in the analysis. A prognostic cut-off value of SUA able to discriminate combined CBV events (>4.79 mg/dL or >284.91 µmol/L) was identified by means of receiver operating characteristic curve in the whole database. Multivariate Cox regression analysis adjusted for confounders (age, sex, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, body mass index, low-density lipoprotein cholesterol, and use of diuretics) identified an independent association between SUA and combined CBV events in the whole database (HR 1.249, 95% confidence interval, 1.041-1.497, p = 0.016). The results of the present study confirm that SUA is an independent risk marker for CBV events after adjusting for potential confounding variables, including arterial hypertension, and demonstrate that >4.79 mg/dL is a valid prognostic cut-off value.

Interaction of Uric Acid and Neutrophil-to-Lymphocyte Ratio for Cardiometabolic Risk Stratification and Prognosis in Coronary Artery Disease Patients

Oxidative stress and inflammation are key factors in cardiometabolic diseases. We set out to evaluate the relationship between serum uric acid (UA) and the neutrophil-to-lymphocyte ratio (NLR) with cardiometabolic risk factors in coronary artery disease (CAD) patients, and their additive and multiplicative interactive effects on outcomes (cardiac death/CD and hard events (HE)-death plus reinfarction). A total of 2712 patients (67 ± 11 years, 1960 males) who underwent coronary angiography was retrospectively analyzed and categorized into no-CAD patients (n =806), stable-CAD patients (n =1545), and patients with acute myocardial infarction (AMI) (n =361). UA and NLR were reciprocally correlated and associated with cardiometabolic risk factors. During a mean follow-up period of 27 ± 20 months, 99-3.6% deaths, and 213-7.8% HE were registered. The Kaplan-Meier survival estimates showed significantly worse outcomes in patients with elevated UA or NLR levels. Multivariate Cox regression analysis demonstrated that NLR independently predicted CD and HE. There was no multiplicative interaction between UA and NLR; however, the use of measures of additive interaction evidenced a positive additive interaction between UA and NLR for CD and HE. Although it is clear that correlation does not imply causation, the coexistence of NRL and UA appears to have a synergistic effect, providing further information for the risk stratification of CAD patients.

Rethinking Chronic Kidney Disease in the Aging Population

The process of aging population will inevitably increase age-related comorbidities including chronic kidney disease (CKD). In light of this demographic transition, the lack of an age-adjusted CKD classification may enormously increase the number of new diagnoses of CKD in old subjects with an indolent decline in kidney function. Overdiagnosis of CKD will inevitably lead to important clinical consequences and pronounced negative effects on the health-related quality of life of these patients. Based on these data, an appropriate workup for the diagnosis of CKD is critical in reducing the burden of CKD worldwide. Optimal management of CKD should be based on prevention and reduction of risk factors associated with kidney injury. Once the diagnosis of CKD has been made, an appropriate staging of kidney disease and timely prescriptions of promising nephroprotective drugs (e.g., RAAS, SGLT-2 inhibitors, finerenone) appear crucial to slow down the progression toward end-stage kidney disease (ESKD). The management of elderly, comorbid and frail patients also opens new questions on the appropriate renal replacement therapy for this subset of the population. The non-dialytic management of CKD in old subjects with short life expectancy features as a valid option in patient-centered care programs. Considering the multiple implications of CKD for global public health, this review examines the prevalence, diagnosis and principles of treatment of kidney disease in the aging population.

Prevalence of Hyperuricemia and Associated Factors Among Type 2 Diabetic Patients in Jordan

Background

Previous studies showed variable estimate of the prevalence of hyperuricemia in patients with type 2 diabetes mellitus (T2DM). The prevalence of hyperuricemia and associated risk factors in Jordanian patients with T2DM is largely unknown. Therefore, this study aimed to determine the prevalence of hyperuricemia and its associated factors in Jordanian patients with T2DM.

Methods

A cross-sectional study was conducted on 655 patients with T2DM. A structured questionnaire was used to collect socio-demographic data. In addition, records of the study subjects were reviewed to obtain other clinical data. Weight, height, and waist circumference were measured, and body mass index was calculated. Lipid profile, serum uric acid and glycated haemoglobin were analysed. The study was conducted in accordance with the Declaration of Helsinki. An informed written consent was obtained from each participant. The confidentiality of the information was assured and only used for scientific purposes.

Results

Overall, the prevalence of hyperuricemia was 28.1%. Female gender (OR: 2.37; 95%, CI: 1.63–3.45), intake of angiotensin-converting enzyme (ACE) and angiotensin-II receptor blockers (ARBs) (OR: 1.68; 95%, CI: 1.12–2.50), intake of β-blockers (OR: 2.20; 95%, CI: 1.51–3.22), increased waist circumference (OR: 3.17; 95%, CI: 1.39–7.22) and family history of hyperuricemia (OR: 2.56; 95%, CI: 1.57–4.16) were associated with increased odds of hyperuricemia.

Conclusion

Hyperuricemia was high among type 2 diabetic patients, and screening test will be useful for those patients.

Factors Associated with Bone Erosion in Patients with Gout: A Dual-Energy Gemstone Spectral Imaging Computed Tomography Study

OBJECTIVE

This study aimed to assess the factors influencing bone erosion in patients with gout using dual-energy gemstone spectral imaging CT.

METHODS

We compared the clinical data, laboratory indices, and tissue urate levels at the monosodium urate (MSU)-bone interface measured by dual-energy gemstone spectral imaging computed tomography of 87 gout patients with (n=41) and without (n=46) bone erosion. Logistic regression analysis was used to investigate the risk factors associated with bone erosion.

RESULTS

In total, 47.1% of patients with gout had bone erosion. The disease duration, serum uric acid, tissue urate levels, and the presence of tophi were significantly higher (p<0.05) in gout patients with bone erosion than in those without bone erosion. Longer disease duration (OR=1.11, 95% CI: 1.00-1.24, p<0.05) and increased tissue urate levels (OR=1.01, 95% CI: 1.00-1.02, p<0.05) were independently associated with bone erosion. Tissue urate levels at the MSU-bone interface were correlated with the presence of tophi (r=0.62, p<0.001), bone erosion (r=0.51, p<0.001), renal calculus (r=0.24, p=0.03), and serum uric acid levels (r=0.23, p=0.03).

CONCLUSION

This study found that longer disease duration and elevated tissue urate concentrations at the MSU-bone interface were associated with bone erosion in patients with gout.

Hyperuricemia in Patients With Coronary Artery Disease and Its Association With Disease Severity

The biochemical background of coronary artery disease (CAD) has been intensively explored in the past several decades. Previous clinical investigations have demonstrated the association of non-traditional risk factors, such as hyperuricemia, with CAD. Studies have shown that increased serum uric acid (SUA) was associated with an increased risk of adverse cardiovascular (CV) outcomes in patients with CAD. While the exact pathophysiological mechanisms leading to increased risk are still unknown, it has been postulated that hyperuricemia leads to endothelial dysfunction, oxidative metabolism, and platelet adhesiveness and aggregation, leading to CAD. Moreover, previous studies have shown that hyperuricemia is an independent risk factor for CAD. However, the correlation between high SUA levels and the severity of CAD remains unclear. The purpose of this review was to elucidate the association of hyperuricemia to CAD severity and to determine the effect of urate-lowering therapy (ULT) on CAD. A search of PubMed up to June 24, 2021, was carried out by the reviewers. From the findings, hyperuricemia stands as an independent risk factor for CAD, and CAD patients treated with ULT had improved CV outcomes and reduced mortality. Therefore, while SUA level is valuable in predicting an augmented risk of CAD and anticipating worse outcomes, ULT has promising cardioprotective effects.

The Clinical Effects of Febuxostat Alone or Combined with Arthroscopic Surgery for Gout: A Single-Center Retrospective Study

Purpose

The purpose of the study was to retrospectively analyze the effects of febuxostat combined with arthroscopic debridement of monosodium urate crystal deposition and febuxostat treatment alone on uric acid levels and acute flares in gout patients.

Patients and Methods

We retrospectively analyzed gout patients who were treated from February 2016 to December 2020. Patients were divided into a control group (febuxostat treatment alone) or a combined group (febuxostat combined with arthroscopic surgery). We recorded and analyzed clinical data including age, sex, body mass index, comorbidities, lesion affected joints, acute flare times, medications history, febuxostat side effects, arthroscopic complications, and serum creatinine and uric acid levels changes.

Results

There were 80 patients in the control group and 93 patients in the combined group. At the beginning of treatment, the combined group had significantly higher disease severity (higher serum uric acid levels and more acute gout flare times). Arthroscopy was performed in 61 knees and 38 ankles, and 86 joints showed crystals deposition. Compared with baseline, follow-up results showed that serum creatinine significantly decreased in the combined group, and serum uric acid and acute gout flare times significantly decreased in both groups (all p < 0.05). In the comparison between the two groups at the follow-up endpoint, acute gout flare times did not differ significantly (p > 0.05), however, serum creatinine and uric acid levels were lower in the combined group compared with those in the control group (ps < 0.05).

Conclusion

Febuxostat combined with arthroscopic debridement of monosodium urate crystal deposition or tophi had a superior effect on lowering uric acid levels and acute flare times in gout patients than did febuxostat alone.

Correlation of Serum Cystatin C with Renal Function in Gout Patients with Renal Injury

The gout-induced continuous deposition of urate in the kidney tissues is the main cause of renal injury, for which cystatin C (Cys C) is an important indicator. This research analyzed the correlation between general renal injury indicators and serum Cys C level, and further investigated the potential of Cys C in renal injury diagnosis. A total of 140 gout patients with renal injury (GRI) were recruited and grouped by their glomerular filtration rate (GFR). Urea nitrogen, uric acid, creatinine, and Cys C levels in the serum were evaluated. The diagnostic efficacy of serum Cys C was evaluated by the nonparametric receiver operating characteristic analysis. Serum Cys C level was increased with decreased GFR in GRI. Urea nitrogen, uric acid, and creatinine levels in the serum showed positive correlations with Cys C level. The area under the curve for serum Cys C was 0.8589 (P < 0.001). In conclusion, this research demonstrated that the serum Cys C level was a precise diagnostic marker for GFR and renal damage evaluation, and showed a significant diagnostic value for renal injury in patients with gout.

Pegloticase treatment of chronic refractory gout: Update on efficacy and safety

Gout is currently the most frequent cause of inflammatory arthritis worldwide. It results from elevated serum urate and subsequent deposition of monosodium urate crystals in joints and other tissues. While many patients with gout can be managed with conventional agents (e.g., allopurinol, febuxostat), those with chronic refractory gout often fail to achieve treatment goals with these agents. Pegloticase is a recombinant, pegylated mammalian uricase developed for treatment of chronic refractory gout. Pegloticase is different than other urate lowering therapies in that it enzymatically degrades urate. Pegloticase has been evaluated in multiple studies, most importantly in two randomized controlled trials and a follow-up open-label extension. Extensive analysis of results from these studies has shown that pegloticase profoundly lowers serum urate, resolves tophi, reduces tender and swollen joint counts, decreases pain, and improves both patients' global assessments and quality of life. Pegloticase also significantly decreases blood pressure in patients with chronic refractory gout, but has no significant effect on renal function. Post hoc analyses of clinical results also indicated that chronic refractory gout patients not achieving sustained urate lowering still have significant clinical benefits with pegloticase treatment. The major limitation of pegloticase is immunogenicity and the emergence of anti-drug antibodies that result in increased drug clearance, loss of efficacy, and infusion reactions. However, these reactions can be avoided by stopping pegloticase when there is a loss of serum urate lowering. New dosing regimens and co-administration of immunosuppressive agents are also being employed to overcome this limitation and extend the benefits of pegloticase to a larger number of patients.

Natural Products and Extracts as Xantine Oxidase Inhibitors - A Hope for Gout Disease?

Xanthine oxidase (EC 1.17.3.2) (XO) is one of the main enzymatic sources that create reactive oxygen species (ROS) in the living system. It is a dehydrogenase enzyme that performs electron transfer to nicotinamide adenine dinucleotide (NAD+), while oxidizing hypoxanthin, which is an intermediate compound in purine catabolism, first to xanthine and then to uric acid. XO turns into an oxidant enzyme that oxidizes thiol groups under certain stress conditions in the tissue. The last metabolic step, in which hypoxanthin turns into uric acid, is catalyzed by XO. Uric acid, considered a waste product, can cause kidney stones and gouty-type arthritis as it is crystallized, when present in high concentrations. Thus, XO inhibitors are one of the drug classes used against gout, a purine metabolism disease that causes urate crystal storage in the joint and its surroundings caused by hyperuricemia. Urate-lowering therapy includes XO inhibitors that reduce uric acid production as well as uricosuric drugs that increase urea excretion. Current drugs that obstruct uric acid synthesis through XO inhibition are allopurinol, febuxostat, and uricase. However, since the side effects, safety and tolerability problems of some current gout medications still exist, intensive research is ongoing to look for new, effective, and safer XO inhibitors of natural or synthetic origins for the treatment of the disease. In the present review, we aimed to assess in detail XO inhibitory capacities of pure natural compounds along with the extracts from plants and other natural sources via screening Pubmed, Web of Science (WoS), Scopus, and Google Academic. The data pointed out to the fact that natural products, particularly phenolics such as flavonoids (quercetin, apigenin, and scutellarein), tannins (agrimoniin and ellagitannin), chalcones (melanoxethin), triterpenes (ginsenoside Rd and ursolic acid), stilbenes (resveratrol and piceatannol), alkaloids (berberin and palmatin) have a great potential for new XO inhibitors capable of use against gout disease. In addition, not only plants but other biological sources such as microfungi, macrofungi, lichens, insects (silk worms, ants, etc) seem to be the promising sources of novel XO inhibitors.

Presence of tophi is associated with a rapid decline in the renal function in patients with gout

We aimed to compare clinical characteristics of patients with and without tophi at the time of the diagnosis of gout and investigate the association of tophi and renal function in gout patients. The patients who were first diagnosed with gout at the Kangwon National University Hospital were retrospectively studied. Patients were divided into 2 groups according to the presence of tophi at the diagnosis. We compared clinical characteristics and the progression of renal dysfunction between the two groups. Of 276 patients, 66 (25.5%) initially presented with tophi. Tophi group was older, had a longer symptom duration, and a higher prevalence of multiple joint involvement than those without tophi. In multivariate logistic regression analysis, prolonged symptom duration and multiple joint involvement were significantly associated with increased risk of formation of tophi. The decline in the eGFR was more prominent in patients with tophi than in those without (- 4.8 ± 14.5 vs. - 0.7 ± 11.9 ml/min/1.73 m²/year, respectively; P = 0.039). The presence of tophi was significantly associated with a rapid decline in the eGFR (β = - 0.136; P = 0.042). In conclusion, the presence of tophi was associated with a rapid declining renal function. Therefore, an early diagnosis and closely monitoring of renal function might be important in gout patients with tophi.

Serum uric acid and fatal myocardial infarction: detection of prognostic cut-off values: The URRAH (Uric Acid Right for Heart Health) study

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Objective:

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad-hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting fatal myocardial infaction (MI) in women and men.

Methods:

The URic acid Right for heArt Health study is a nationwide, multicentre, observational cohort study involving data on individuals aged 18–95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 122.3 ± 66.9 months.

Results:

A total of 23 467 individuals were included in the analysis. Cut-off values of SUA able to discriminate MI status were identified by mean of receiver operating characteristic curves in the whole database (>5.70 mg/dl), in women (>5.26 mg/dl) and in men (>5.49 mg/dl). Multivariate Cox regression analyses adjusted for confounders (age, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, BMI, haematocrit, LDL cholesterol and use of diuretics) identified an independent association between SUA and fatal MI in the whole database (hazard ratio 1.381, 95% confidence intervals, 1.096–1.758, P = 0.006) and in women (hazard ratio 1.514, confidence intervals 1.105–2.075, P < 0.01), but not in men.

Conclusion:

The results of the current study confirm that SUA is an independent risk factor for fatal MI after adjusting for potential confounding variables, and demonstrate that a prognostic cut-off value associated to fatal MI can be identified at least in women.

Characteristics, Comorbidities, and Potential Consequences of Uncontrolled Gout: An Insurance-Claims Database Study

INTRODUCTION

Gout is a common, progressive, systemic inflammatory arthritis caused by hyperuricemia. Current guidelines recommend that serum uric acid (sUA) levels be maintained below 6.0 mg/dl to minimize acute gout attacks, tophi development, and long-term joint and organ damage. This study examined the influence of uncontrolled gout on post-diagnosis comorbidities and medication use.

METHODS

The Humana Research Database (2007-2016, commercial insurance and Medicare) was searched (PearlDiver tool) for patients who had a gout diagnosis code, claims data for at least 6 months before and after diagnosis, and at least 90 days of continuous urate-lowering therapy within 1 year of diagnosis. Patients with controlled (all sUA measurements < 6.0 mg/dl) and uncontrolled (all sUA measurements ≥ 8.0 mg/dl) gout were further examined and compared to better understand the influence of uncontrolled gout on post-diagnosis comorbidities, medication use, and reasons for seeking medical care.

RESULTS

A total of 5473 and 1358 patients met inclusion and classification criteria for the controlled and uncontrolled groups, respectively. Identified comorbidities in both groups included hypertension, hyperlipidemia, diabetes, cardiovascular disease, and chronic kidney disease (CKD). However, the uncontrolled group was more likely to have diabetes, CKD, and cardiovascular disease (including heart failure and atrial fibrillation). Additionally, CKD tended to be more advanced in the uncontrolled gout population (Stage 4-5: 34.6 vs. 22.2%). Overall opioid use was higher in uncontrolled patients.

CONCLUSIONS

The current study identified differences between controlled and uncontrolled gout patients, including usage of medication, severity of CKD, and prevalence of CKD, diabetes, and heart disease.

An LC-MS/MS- and hURAT1 cell-based approach for screening of uricosuric agents

Urate anion exchanger 1 (URAT1) expressed in the proximal renal tubules is responsible for about 90% of the reabsorption of uric acid. URAT1 is identified as an important target of uricosuric drugs. Here we present an LC-MS/MS-based approach, combined with URAT1-transgenic MDCK cells, for the assessment of uric acid. Cell lysis was executed with 50 mM NaOH to release uric acid. 1,3-¹⁵N₂ uric acid was employed as the internal standard. The harvested uric acid, along with the stable isotope-labeled uric acid, was analyzed by LC-MS/MS in multiple reactions monitoring and negative modes. Validation, i.e. determination of selectivity, precision, accuracy, extraction recovery, and matrix effect, and feasibility was evaluated by use of the approach developed. The linearity was observed in the range of 1.0-250 μM (r = 0.9960) with limit of detection of 50 nM and limit of quantitation of 200 nM. The precision and accuracy were found to be RSD ≤ 20% and 80-120% of the nominal value, respectively. Uric acid uptake showed concentration and time dependency in URAT1-transgenic cells. The observed inhibitory effects of three URAT1-targeted uricosuric drugs were consistent with those reported in literature. The stable isotope dilution-based approach was proven to be selective, sensitive, and convenient, which is a good in vitro model for URAT1-targeted drug candidate screening.

Xanthine Oxidase and Transforming Growth Factor Beta-activated Kinase 1: Potential Targets for Gout Intervention

BACKGROUND

Gout, inflammatory arthritis caused by the deposition of monosodium urate crystals into affected joints and other tissues, has become one of the major health problems of today's world. The main risk factor for gout is hyperuricemia, which may be caused by excessive or insufficient excretion of uric acid. The incidence is usually in the age group of 30- 50 years, commonly in males. In developed countries, the incidence of gout ranges from 1 to 4%. Despite effective treatments, there has been an increase in the number of cases over the past few decades.

OBJECTIVE

In recent years, the development of targeted drugs in gout has made significant achievements. The global impact of gout continues to increase, and as a result, the focus of disease-modifying therapies remains elusive. In addition, the characterization of available instrumental compounds is urgently needed to explore the use of novel selective and key protein-ligand interactions for the effective treatment of gout. Xanthine oxidase (XO) is a key target in gout to consider the use of XO inhibitors in patients with mild to moderate condition, however, the costs are high, and no other direct progress has been made. Despite many XO inhibitors, a selective potent inhibitor for XO is limited. Likewise, in recent years, attention has been focused on different strategies for the discovery and development of new selectivity ligands against transforming growth factor beta- activated kinase 1 (TAK1), a potential therapeutic target for gout. Therefore, the insight on human XO structure and TAK1 provides a clue into protein-ligand interactions and provides the basis for molecular modeling and structure-based drug design.

CONCLUSION

In this review, we briefly introduce the clinical characteristics, the development of crystal, inhibitors, and crystal structure of XO and TAK1 protein.

Hyperuricemia is a Risk Factor for One-Year Overall Survival in Elderly Female Patients with Acute Coronary Syndrome

Background

Hyperuricemia is a risk factor for cardiovascular diseases, but the impact of hyperuricemia and sex-related disparities is not fully clear in elderly patients with acute coronary syndrome (ACS).

Objective

To investigate the association between hyperuricemia and 1-year all-cause mortality in elderly patients with ACS.

Methods

This retrospective cohort study included 711 consecutive ACS patients aged ≥75 years, hospitalized in our center between January 2013 and December 2017. Serum uric acid (sUA), in-hospital events, and 1-year follow-up were analyzed. Multivariable logistic regression models were used to explore the risk factors for in-hospital events and 1-year all-cause mortality.

Results

sUA levels were higher in males than in females (381.4 ± 110.1 vs. 349.3 ± 119.1 μmol/l, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%,

Conclusions

Hyperuricemia is an independent risk factor for 1-year all-cause mortality in elderly female patients with ACS.

The Impact of Natural Product Dietary Supplements on Patients with Gout: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Natural product dietary supplements (NPDS) are frequently used for the treatment of gout, but reliable efficacy and safety data are generally lacking or not well organized to guide clinical decision making. This review aims to explore the impacts of NPDS for patients with gout. An electronic literature search was conducted to retrieve data published in English language from databases from inception to August 14, 2019. Randomized controlled trials (RCTs) that compared NPDS with or without placebo, diet modification, conventional pharmaceutics, or the other Chinese medicine treatment for gout patients were included. Two authors screened the articles, extracted the data, and assessed the risk of bias of each included trial independently. Meta-analysis was performed using Review Manager version 5.3.5. Results. Nine RCTS were enrolled in this review. The methodological quality of the nine RCTs was poor. The study results showed that in the majority of trials, NPDS demonstrated some degree of therapeutic efficacy for joint swelling, pain, and activity limitation. In contradistinction, serum uric acid (SUA) level (SMD -1.80, 95% CI: -4.45 to 0.86) (p > 0.05) and CRP levels (N = 232; SMD, -0.26; 95% CI, -0.55 to 0.04) (p > 0.05) did not improve significantly. The incidence of adverse events (AEs) was not lower in the participants treated with NPDS (N = 750; RR, 0.47; 95% CI, 0.20-1.11) (p > 0.05). Conclusion. Current existing evidence is not sufficient to provide clinical guidance regarding the efficacy and safety of NPDS as a treatment for gout due to poor trial quality and lack of standardized evaluation criteria. Larger and more rigorously designed RCTs are needed in the future.

A Randomized, Double-Blind, Non-Inferiority Study of Febuxostat Versus Allopurinol in Hyperuricemic Chinese Subjects With or Without Gout

Introduction

This 24-week randomized, double-blind, non-inferiority study compared the efficacy and safety of febuxostat, a xanthine oxidase inhibitor, with allopurinol using an up-titration method in hyperuricemic Chinese subjects with or without gout.

Methods

Eligible adults (serum uric acid [SUA] > 7.0 mg/dl with a history of gout, SUA ≥ 8.0 mg/dl with complications or SUA ≥ 9.0 mg/dl without complications) were randomized (1:1:1) to febuxostat 40 mg/day, 80 mg/day, or allopurinol 300 mg/day. Starting doses of febuxostat 20 mg/day and allopurinol 100 mg/day were up-titrated, up to 16 weeks, to the randomized doses and maintained to week 24. Primary endpoint was non-inferiority of febuxostat 40 mg/day versus allopurinol 300 mg/day based on the percentage of subjects with SUA ≤ 6.0 mg/dl at week 24. The same comparison was made between febuxostat 60 mg/day or 80 mg/day versus allopurinol 300 mg/day. Safety assessments included measurement of treatment-emergent adverse events (TEAEs).

Results

The per-protocol population comprised 472 subjects. Non-inferiority of febuxostat 40 mg/day versus allopurinol 300 mg/day was not demonstrated based on the protocol-defined margin of − 10% (44.7 vs. 50.0%; − 5.3% difference; 95% confidence interval [CI]: − 16.4%, 5.8%); however, superiority over allopurinol 300 mg/day was demonstrated for febuxostat 60 mg/day at week 16 (66.3 vs. 51.2%; a 15.0% difference; 95% CI: 4.2%, 25.9%) and febuxostat 80 mg/day at week 24 (70.0 vs. 50.0%; a 20.0% difference; 95% CI: 9.3%, 30.7%). The frequency of TEAEs was similar across groups, with gout flares occurring frequently.

Conclusions

Using a novel dose-titration method, although the primary endpoint of non-inferiority of febuxostat 40 mg/day versus allopurinol 300 mg/day was not reached, non-inferiority and superiority of febuxostat 60 mg/day and 80 mg/day versus allopurinol 300 mg/day was demonstrated at weeks 16 and 24, respectively. Febuxostat demonstrated an acceptable tolerability profile in the treatment of hyperuricemia in Chinese subjects with or without gout.

Trial Registration

JapicCTI-132106.

Funding

Astellas Pharma Global Development, Inc.

Electronic Supplementary Material

The online version of this article (10.1007/s40744-019-00173-8) contains supplementary material, which is available to authorized users.

Bone mineral density and serum osteocalcin levels in patients with gout

Objective: The objective of the study is to evaluate the relation of gout with osteoporosis and serum osteocalcin (OC) levels. Material and methods: Seventy-five patients diagnosed with gout and 55 controls were included in the study. Comorbid conditions and drugs associated with osteoporosis were excluded. The T and Z scores from lumbar spine (L2-L4) and femur (neck, ward, trochanter, total) were determined by dual-energy X-ray absorptiometry (DXA). OC levels were measured by enzyme-linked immunosorbent assay. Results: Osteoporosis according to T scores of lumbar vertebrae L2-L4 was found to be significantly higher in patients with gout compared to the control group (p = 0.02). Lumbar spine T-score was -1.6 in gout group and -1.0 in controls. OC level was 7.9 ng/mL in the gout group and 18.9 ng/mL in the control group. There was a significant difference (p < 0.001). In addition, mean OC level was 12.4 ± 6.9 ng/mL in the patients diagnosed with osteoporosis and 17.2 ± 10.6 ng/mL in the patients that were classified as normal and a significant difference was established between the two groups (p = 0.03). A significant negative correlation was found between OC level and body mass index, age, and age at first attack. Similarly, femoral T-score established a negative correlation with parathyroid hormone, age, age at first attack, and allopurinol dose. Conclusion: Serum OC level can be a useful marker in the assessment of bone turnover and clinicians should keep osteoporosis in mind in gout patients.

Gout and hyperuricaemia in the USA: prevalence and trends

Objectives

Several recent observations have suggested that the prevalence of gout may be increasing worldwide, but there are no recent data from the USA. We analysed the prevalence of hyperuricaemia and gout in the US population from 2007–08 to 2015–16.

Methods

We studied adults ⩾20 years of age from the National Health and Nutrition Examination Survey from 2007–08 to 2015–16. Persons with gout were identified from the home interview question ‘Has a doctor or other health professional ever told you that you had gout?’ Hyperuricaemia was defined as a serum urate level >0.40 mmol/l (6.8 mg/dl) (supersaturation levels at physiological temperatures and pH).

Results

In 2015–16, the overall prevalence of gout among US adults was 3.9%, corresponding to a total affected population of 9.2 million. Hyperuricaemia (>0.40 mmol/l or 6.8 mg/dl) was seen in 14.6% of the US population (estimated 32.5 million individuals). No significant trends were identified in the age-adjusted prevalence of gout and hyperuricaemia. Statistical comparisons between 2007–08 and 2015–16 age-adjusted rates were not significant.

Conclusion

While the age-adjusted prevalence of gout and hyperuricaemia has remained unchanged in the most recent decade from 2007–08 to 2015–16, the estimated total number of persons with self-reported gout has increased from 8.3 million to 9.2 million. The age-adjusted prevalence of hyperuricaemia has declined slightly, but the total number of affected individuals is virtually identical (32.5 million in 2015–16 compared with 32.1 million in 2007–08).

Efficacy and safety of lesinurad for the treatment of hyperuricemia in gout

The aim of this review is to present current evidence about the efficacy and safety of lesinurad in combination with xanthine oxidase inhibitors (XOIs) in the treatment of hyperuricemia in patients with gout. Gout is the most common inflammatory form of arthritis. It is caused by an elevated concentration of serum uric acid (UA) that leads to the formation of monosodium urate crystals in joints and different tissues. The goal of therapy is to maintain serum UA levels at <6 mg/dL (0.36 mmol/L), to prevent the formation and deposition of monosodium urate crystals, and to dissolve existing crystals. Lesinurad, a new uricosuric, increases renal urate excretion by selectively inhibiting the renal uric acid transporter 1 (URAT1). Lesinurad is indicated in adults, in combination with a XOI, for the adjunctive treatment of hyperuricemia in patients with gout (with or without tophi) who have not achieved target serum UA levels with an adequate dose of a XOI alone. With the combination strategy, serum UA targets could be reached with the consequence of inhibiting formation of new crystals and promoting dissolution of existing crystals and, therefore, inducing improvement of outcomes such as flares and tophi. The approval of lesinurad was based on data from three pivotal phase III studies (CLEAR 1, CLEAR 2, and CRYSTAL). These clinical studies assessed lesinurad 200 and 400 mg doses. As only lesinurad 200 mg/day dose was finally approved and commercialized, it will be the focus of this paper. In the pivotal clinical trials, the target serum UA level was achieved by significantly more patients in lesinurad 200 mg plus allopurinol group (CLEAR 1 and CLEAR 2 trials) or lesinurad 200 mg plus febuxostat group (CRYSTAL study) compared with patients who received either XOI alone. In these trials, the safety profile of lesinurad 200 mg plus a XOI was comparable to allopurinol or febuxostat alone. Lesinurad, in combination with a XOI, is an effective and safe treatment that covers unmet needs in adults with gout who have not achieved target serum UA levels with a XOI alone.

Characterization of patients with chronic refractory gout who do and do not have clinically apparent tophi and their response to pegloticase

OBJECTIVES

To determine the characteristics and response to pegloticase of patients with chronic refractory gout with and without clinically apparent tophi.

METHODS

Results from two randomized controlled trials of pegloticase in patients with chronic refractory gout with clinically apparent tophi or without tophi were used to assess baseline and on-treatment between-group differences.

RESULTS

Patients with tophi were significantly older than those without tophi, had a significantly longer duration of disease, higher numbers of tender and swollen joints, higher Patient Global Assessment scores and Health Assessment Questionnaire-Disability Index scores, and lower Arthritis-Specific Health Index scores. Patients with tophaceous gout also had significantly lower scores for physical functioning, role physical, social functioning, and the physical component summary scores of the Short Form 36 vs patients without tophi. In addition, subjects with clinically apparent tophi had a significantly lower mean estimated glomerular filtration rate. Pegloticase treatment of tophaceous patients caused significant reductions in serum urate, flares, Patient Global Assessment, tender joints, swollen joints, Health Assessment Questionnaire-Disability Index, visual analogue scale pain and Short Form 36 Bodily Pain, whereas patients without tophi had significant improvement in serum urate, flares, Patient Global Assessment, tender joints, and Short Form 36 Bodily Pain, but not swollen joints, Health Assessment Questionnaire-Disability Index functional score or pain visual analogue scale. Treatment with pegloticase had no effect on estimated glomerular filtration rate despite significant lowering of the urinary uric acid: creatinine ratio.

CONCLUSION

Patients with chronic refractory gout and clinically apparent tophi have more severe disease as well as reduced renal function. Both groups experienced significant clinical benefit with pegloticase treatment, although no change in renal function was noted.

Tophus resolution in patients with chronic refractory gout who have persistent urate-lowering responses to pegloticase

BACKGROUND

Pegloticase is a recombinant mammalian uricase conjugated to polyethylene glycol approved in the United States for treatment of chronic refractory gout. It can profoundly decrease serum urate to < 1 mg/dl. In patients receiving pegloticase who did not generate high-titer antidrug antibodies (responders), the serum urate remained low for the duration of therapy, 6 months in the phase III clinical trials plus the open-label extension. The objective of this study was to assess the velocity of tophus resolution in subjects treated with pegloticase.

METHODS

Data from two randomized controlled trials of pegloticase in chronic refractory gout were analyzed. Tophi were assessed by computer-assisted measurements of standardized digital photographs. Subjects were designated as responders and nonresponders based on maintenance of serum urate < 6 mg/dl at months 3 and 6 of treatment. The projected time of complete resolution of all tophi was determined by linear regression analysis.

RESULTS

The mean total tophus area at baseline was 585.8 mm² for responders, 661.5 mm² for nonresponders, and 674.4 mm² for placebo-treated patients. Complete resolution at 6 months of at least one tophus was achieved by 69.6% of 23 responders, 27.9% of 43 nonresponders, and 14.3% of 21 patients who received placebo. Complete resolution of all photographed tophi was achieved by 34.8% of biochemical responders, 11.6% of nonresponders, and 0% of placebo-treated patients. The mean velocity of resolution of all tophi was 60.1 mm²/month in responders with a mean projected time of complete resolution of 9.9 months (4.6-32.6 months). There was a significant inverse correlation between serum urate AUC and tophus resolution velocity (r = - 0.40, P = 0.0002), although considerable heterogeneity in the velocity of resolution was noted. The only patient characteristic that correlated with the velocity of tophus resolution was the baseline tophus area.

CONCLUSIONS

Pegloticase treatment caused a rapid resolution of tophi in responders that correlated with the serum urate lowering associated with this therapy.

Metabolic Epoxidation Is a Critical Step for the Development of Benzbromarone-Induced Hepatotoxicity

Benzbromarone (BBR) is effective in the treatment of gout; however, clinical findings have shown it can also cause fatal hepatic failure. Our early studies demonstrated that CYP3A catalyzed the biotransformation of BBR to epoxide intermediate(s) that reacted with sulfur nucleophiles of protein to form protein covalent binding both in vitro and in vivo. The present study attempted to define the correlation between metabolic epoxidation and hepatotoxicity of BBR by manipulating the structure of BBR. We rationally designed and synthesized three halogenated BBR derivatives, fluorinated BBR (6-F-BBR), chlorinated BBR (6-Cl-BBR), and brominated BBR (6-Br-BBR), to decrease the potential for cytochrome P450-mediated metabolic activation. Both in vitro and in vivo uricosuric activity assays showed that 6-F-BBR achieved favorable uricosuric effect, while 6-Cl-BBR and 6-Br-BBR showed weak uricosuric efficacy. Additionally, 6-F-BBR elicited much lower hepatotoxicity in mice. Fluorination of BBR offered advantage to metabolic stability in liver microsomes, almost completely blocked the formation of epoxide metabolite(s) and protein covalent binding, and attenuated hepatic and plasma glutathione depletion. Moreover, the structural manipulation did not alter the efficacy of BBR. This work provided solid evidence that the formation of the epoxide(s) is a key step in the development of BBR-induced hepatotoxicity.

Elevated UMOD methylation level in peripheral blood is associated with gout risk

Uromodulin (UMOD) encodes an uromodulin glycoprotein, and its mutation results in uromodulin glycoprotein dysfunction and the occurrence of gout. The aim of our study was to assess whether UMOD methylation could predict the risk of gout. A total of 89 sporadic gout cases and 103 age and gender-matched healthy controls were recruited in this study. UMOD methylation level was determined by quantitative methylation-specific PCR (qMSP) in peripheral blood, and the percentage of methylated reference (PMR) was described to represent the methylation level. Our results showed that UMOD methylation was significantly higher in gout cases than controls (median: 1.45 versus 0.75, P < 0.001). The area under curve (AUC) of UMOD methylation in gout was 0.764 (P = 2.90E-10) with a sensitivity of 65.2% and a specificity of 88.3%. UMOD methylation level was shown to be significantly correlated with the serum level of uric acid (UA) (r = −0.208, P = 0.035). Besides, the luciferase reporter assay showed that UMOD CpG island region was able to upregulate gene expression (fold change = 2, P = 0.004). In conclusion, UMOD methylation assessment might be used to predict the occurrence of gout.